Without limiting the scope of the present invention, its background will be described in relation to an apparatus for creating bidirectional rotary force or motion in a downhole device and method for using same, as an example.
In producing oil and gas, many different processes, tools, and the like are employed. Oftentimes, the processes and tools used may become impediments to subsequent processes. For example, hydraulic fracturing a well typically includes drilling a wellbore, such as a horizontal wellbore through hydrocarbon bearing formations. Typically, once the wellbore is drilled, casing is run into the wellbore and cemented in place. Once cemented, one or more tools are run into the wellbore to perforate the casing, cement, and formation. These perforating devices may be any types commonly known, such as abrasive or pyrotechnic perforators. The perforating devices create perforations through the casing, cement, and formation for enabling a fracturing fluid to be pumped under high pressure from the passageway of the casing string through the perforations into the formations to create fractures in the formation for improving the recovery of hydrocarbons in a particular zone of the well.
To fracture another zone above the one previously fractured, a drillable bridge plug, a setting tool, and a perforating device may be run into the well via an electricline, wireline, and the like. These tools may be transported through the horizontal sections of the well with a fluid. The bridge plug is then set with the setting tool, and then the perforating device may be operated to perforate the wellbore above where the bridge plug is set. After perforating the zone, the setting tool and perforating device may be removed from the wellbore and fracturing fluid with proppant may be pumped into the zone to fracture the formation. The process may be repeated as many times as desired.
All of these set bridge plugs seal the central passageway within the casing and prevents hydrocarbons from being produced through the casing. To clear the bridge plugs from the passageway, additional tools may be run into the wellbore to mechanically mill or grind them to clear the passageway. This method is known as “plug and perf.”
An alternative to the plug and perf method is to incorporate sleeve valves with ports in the casing string. The sleeve valves are spaced out along the casing string prior to running them into the wellbore. Once the casing string is run into the wellbore, the lower or bottom sleeve valve may be opened, exposing ports in the sleeve valve creating a passageway from the inner casing to the formation substantially adjacent to the sleeve valve. Typically, these sleeve valves are opened by applying a fluid under pressure to the sleeve valve to be opened. Once the sleeve valve is opened, fracturing fluid with proppant is pumped to the bottom zone and through the sleeve valve to fracture the bottom zone of the formation.
When a sufficient amount of proppant is injected into the fractured formation, a drillable ball may be dropped into the fluid which flows with the fluid to the opened sleeve valve. Typically, each of the sleeve valves includes a seat or baffle that the ball lands on. The baffle of the lowermost sleeve valve is smaller in diameter than the seat of the sleeve valve located above it. The diameter of the baffles of the sleeve valves are progressively smaller to larger from the bottom to the top of the wellbore. A small ball is dropped first and seals to a baffle that is directly above the zone that was just fractured, thus closing off fluid communication to the opened sleeve valve. Once the ball seats against the baffle, the fluid pressure increases causing the sleeve valve located above the sealed baffle to shift open. This then opens ports in the sleeve valve. This fracturing process may be repeated by dropping balls having increasing size to seal off sleeve valves of increasing baffle size from the toe to the heel of the wellbore. One problem with this method is that all of the seated balls must then be mechanically milled out the balls and baffles to clear the inner diameter of the wellbore passageway. In addition, ball and baffle systems are limited because of the available ball size increments, thus they limit the number of valves that can be run on a single casing string.
Another problem associated with this method is that the sleeve valves open axially linearly, thus requiring a need for an area or space for the sleeve to slide linearly into when opening to expose the ports.
Yet another problem with ball and baffle methods is during the cementing operation, cement becomes lodged in the baffles disposed within the casing string. The conventional cementing method is to run in a casing string into the wellbore, set a cement plug, and put a column of cement behind the first cement plug on the bottom. Additionally, another plug may be put on the top of the cement to isolate it from a fluid, such as mud, above that is used to push the cement column between the wellbore and the outer surface of the casing string. Existing baffles in the casing string interfere with the plugs providing a clean wipe down through the casing string passageway. Plus, the lower baffle may have such a small opening, that plugs may have a difficulty passing through the baffle and also because some of the cement accumulates around the baffle. This can be a further problem when a sleeve valve that must move axially is impeded by the cement disposed within the inner passageway of the casing string.
Also, conventional systems and methods may use swellable packers that are disposed between the outside of the casing string and the wellbore isolating the fracturing zones. In such cases, swellable packers are used in place of cement.